The present invention relates to coating materials used for example in insulation, shock absorption, cushioning, packaging. Specifically, the present invention relates to elastic coating materials.
Coated articles and in particular coating materials comprising olefinic polymers are well known in the art and enjoy widespread usage throughout the industry. Typical areas of application of such coating material include hygienic articles and in particular disposable absorbent articles, packaging materials.
Coating materials made from commonly used polyolefins such as PP, PE, PS PIB have a number of useful properties. They are bio-compatible and food compatible, chemically stabile, inert, non toxic materials. However, most of them are rigid and have poor mechanical properties including insufficient strength/tear resistance, insufficient stretchability/elasticity and the like.
Several approaches have been proposed in the prior art to provide elastic properties to such polymeric coating materials. The most commonly used approach is based on changing the chemical structure of the polymer by introducing hinged joints/moieties into the main chain of the polymer. These hinges provide more flexibility to the polymeric backbone preventing crystallization of polymer, lowering the glass transition temperature (Tg) and improving the elasticity of the resulting material. Usually, the hinge groups contain heteroatoms providing flexibility such as oxygen, nitrogen or chlorine placed into the main chain or into bulky side groups. Another approach is mastication of the polymer by blending with special plasticizing agents. Both approaches, however, require heteroatoms to be introduced into the molecule or into the bulk of the coating material.
The third approach proposed in the prior art to provide elastic properties to such polymeric coating materials, which is more close to the present invention, is to exploit the formation of hetero-phases which reinforce the bulk material by forming a physical net. To do this the block-co-polymerization of two or more different monomers has been used leading to polymeric backbones comprising blocks with different Tg. This results in micro-phase separation in the bulk with formation of reinforcing crystalline domains of one co-polymer linked with each other by flexible chains of the second co-polymer.
In essence, conventional polymeric coating material carry a wide variety of inherent disadvantages including but not being limited to insufficient strength/tear resistance, insufficient stretchability/elasticity, not being bio-compatible, not being food compatible, comprising heteroatoms such as chlorine and hence leading to toxic residues when burnt, and the like.
It is an object of the present invention to provide coating materials which overcome the disadvantages of the prior art coating materials.
It is an further object of the present invention to provide articles which comprise elastic coating materials.
It is an further object of the present invention to provide a method for manufacturing a coated article of the present invention.
The present invention provides a coating composition for covering at least a portion of the surface of an element with a polymeric coating characterized in that said coating composition comprises a polyolefinic homopolymer having an isotacticity of less than 60% of [mmmm] pentad concentration.
The present invention further provides an article comprising an element and the aforementioned polymeric coating material covering at least portion of the surface of said element.
The present invention further provides a method for coating an element with the aforementioned polymeric coating material comprising a step selected from the group of dip coating, spray coating, emulsion coating, and combinations thereof.